1. Technical Field
The present invention relates to a liquid crystal device.
2. Related Art
A known liquid crystal device disclosed in, for example, Japanese Unexamined Patent Application Publication No. 2007-256905 has the structure including a liquid crystal layer disposed between a pair of substrates. One of the substrates has a plurality of pixel electrodes provided for respective pixels. The pixel electrodes are covered with an insulating layer. On the insulating layer, a common electrode having a plurality of slits is formed over the plurality of pixels. The common electrode and the pixel electrodes generate an electric field therebetween. The electric field turns liquid crystal molecules of the liquid crystal layer in a predetermined direction from an initial orientation in the regions corresponding to the slits.
In the known liquid crystal device, undesirably, there occur regions where the electric field E generated between the common electrode 41 and the pixel electrodes 11 is tilted in opposite directions in regions corresponding to the slits 41a such that the electric field E at both sides 11e of the pixel electrode 11 is tilted in a direction opposite to the direction in which the electric field E around the center 11c of the pixel electrode 11 is tilted, as shown in FIGS. 5A and 5B.
The slit 41a of the common electrode 41 has a straight portion 41s extending in the direction in which the slit extends. The straight portion 41s is generally formed so as to extend substantially along the initial orientation D of the liquid crystal molecules M, but forming a small angle with the initial orientation D of the liquid crystal molecules M. For example, the straight portion 41s of the slit 41a has a small angle in a positive direction with respect to the initial orientation D of the liquid crystal molecules M. In this instance, at the center 11c of the pixel electrode 11 in the region corresponding to the slit 41a, the electric field E is oriented in a direction substantially perpendicular to the straight portion 41s of the slit 41a, and thus the electric field E has an angle in a negative direction.
At the sides 11e of the pixel electrode 11 in the region corresponding to the slit 41a of the common electrode 41, the pixel electrode extend in the direction substantially perpendicular to the initial orientation D of the liquid crystal molecules M. Consequently, there is produced a revere tilt domain R at both sides 11e of the pixel electrode 11. In the reverse tilt domain, the electric field is oriented in a positive direction, hence in the opposite direction to the orientation of the electric field E at the center 11c of the pixel electrode 11.
In the reverse tilt domain R, when an electric field E is generated, the liquid crystal molecules M are turned in a direction RI opposite to the direction RD in which the liquid crystal molecules M around the center 11c of pixel electrode 11 are turned from the initial orientation. Accordingly, in the reverse tilt domain R, the liquid crystal molecules M are oriented in a different direction from the direction around the center 11c of the pixel electrode 11 when an electric field E is generated. Consequently, the quality of displayed images is degraded.